Cannot use instance member within property initializer

Question

Created Jun ’23

Replies 3

Boosts 1

Views 1.2k

Participants 4

I've been trying to use the example from this session to tweak the default SwiftData template, allowing for syncing of the data across devices. When I added the following code, I get the above error:

@main
struct ItemApp: App {
    let items = ModelConfiguration(schema: Schema([Item.self]), url: URL(filePath: "/path/to/item.store"),  cloudKitContainerIdentifier: "iCloud.com.app.Item")
    let container = try ModelContainer(for: items). // ERROR HERE

    
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .modelContainer(container)
    }
}

Cannot use instance member 'items' within property initializer; property initializers run before 'self' is available

Any pointers would be helpful.

Boost

Answer 1

Claude31 OP

Jun ’23

You could replace the let contained by a computed var, something like this

var container : ModelContainer {  // I suppose it is this type
  let cont = try ModelContainer(for: items)
  return cont 
}

You could call

    let items = ModelConfiguration(schema: Schema([Item.self]), url: URL(filePath: "/path/to/item.store"),  cloudKitContainerIdentifier: "iCloud.com.app.Item")

in the computed var if you don't need items elsewhere.

Or create an explicit init.

Or set in .onAppear

0

Answer 2

alexander216 OP

Jun ’23

I noticed the same! The code the session uses at 6:58 isn’t working. The .modelContainer(for: [Trip.self, BucketListItem.self, LivingAccommodation.self]) code you’ve mentioned in the other comment is only for simple cases, and not really something to achieve the customization like yours …

0

Answer 3

CryptoKoa OP

Jun ’23

To make it explicit, this works:

@main
struct SwiftDataFlashCardSample: App {
   let container: ModelContainer
   
   init() {
      let schema = Schema([Card.self])
      let config = ModelConfiguration(schema: schema, cloudKitContainerIdentifier: "iCloud.org.your.name")
      var contain: ModelContainer? = nil
      do {
         contain = try ModelContainer(for: schema, config)
      } catch {
         print("couldn't create ModelContainer()")
      }
      self.container = contain!
   }
   var body: some Scene {
      WindowGroup {
         ContentView()
      }
      .modelContainer(container)
   }
}

and, as normal, add Capabilities iCloud.cloudKit and BackgroundModes.Remote notifications.

0